Wash the potatoes and cook in plenty of boiling water for about 20 minutes. In the meantime peel and chop the onions. Cut the bacon into fine cubes as well. Wash chives, dab dry and cut into small rolls.
Remove the fish fillets from the bones, remove the skin as desired and cut the fillets into pieces. Drain the potatoes, rinse under cold water and peel the skin. Cut the potatoes into slices.
Put the bacon in a hot pan and let it crisp. Add onions at the end and fry briefly. Remove bacon and onions from the pan. Add oil to the hot bacon fat, heat up and fry the potato slices until golden brown, turning them over.
Add bacon and onions and season with salt and pepper. Add the fish to the potatoes. Whisk eggs, milk and mustard. Add chives, except for something to sprinkle. Pour mixture over the potato and fish pan and let it simmer at low to medium heat.
Serve sprinkled with remaining chives. Sour vegetables taste good with it.